CD40 induces macrophage anti–Toxoplasma gondii activity by triggering autophagy-dependent fusion of pathogen-containing vacuoles and lysosomes
Rosa M. Andrade, Matthew Wessendarp, Marc-Jan Gubbels, Boris Striepen, Carlos S. Subauste
Rosa M. Andrade, Matthew Wessendarp, Marc-Jan Gubbels, Boris Striepen, Carlos S. Subauste
View: Text | PDF
Research Article Infectious disease

CD40 induces macrophage anti–Toxoplasma gondii activity by triggering autophagy-dependent fusion of pathogen-containing vacuoles and lysosomes

Abstract

Many intracellular pathogens, including Toxoplasma gondii, survive within macrophages by residing in vacuoles that avoid fusion with lysosomes. It is important to determine whether cell-mediated immunity can trigger macrophage antimicrobial activity by rerouting these vacuoles to lysosomes. We report that CD40 stimulation of human and mouse macrophages infected with T. gondii resulted in fusion of parasitophorous vacuoles and late endosomes/lysosomes. Vacuole/lysosome fusion took place even when CD40 was ligated after the formation of parasitophorous vacuoles. Genetic and pharmacological approaches that impaired phosphoinositide-3-class 3 (PIK3C3), Rab7, vacuolar ATPase, and lysosomal enzymes revealed that vacuole/lysosome fusion mediated antimicrobial activity induced by CD40. Ligation of CD40 caused colocalization of parasitophorous vacuoles and LC3, a marker of autophagy, which is a process that controls lysosomal degradation. Vacuole/lysosome fusion and antimicrobial activity were shown to be dependent on autophagy. Thus, cell-mediated immunity through CD40 stimulation can reroute an intracellular pathogen to the lysosomal compartment, resulting in macrophage antimicrobial activity.

Authors

Rosa M. Andrade, Matthew Wessendarp, Marc-Jan Gubbels, Boris Striepen, Carlos S. Subauste

×

Figure 4

CD40 stimulation induces fusion of preformed PV and late endosomes/lysosomes.

Options: View larger image (or click on image) Download as PowerPoint
CD40 stimulation induces fusion of preformed PV and late endosomes/lysos...
Bone marrow macrophages from TNF-α–/– mice infected with CPSII KO T. gondii–YFP were incubated overnight in the presence of uracil (0.2 mM) to allow parasite replication. After uracil removal, infected macrophages were cultured with stimulatory anti-CD40 mAb for 24 hours. TNF-α (500 pg/ml) was then added to monolayers, and cells were examined after 7 hours. Arrowheads denote colocalization of LAMP-1 (ring) around PV in CD40-activated macrophage. Scale bar: 5 μm. Results are representative of 4 independent experiments.